Method and apparatus for measuring a height of a vehicle

Abstract

A method of measuring a height of a vehicle on a road comprises recording with a vehicle classification sensor a 3D representation of the vehicle passing the section and recording with a camera a 2D image of at least an upper portion of the vehicle and a background; determining an edge profile between the upper portion and the background establishing a fan of rays each extending from the elevated point and through a different one of multiple points along the edge profile; shifting the 3D representation in the coordinate system in height until it is tangent to said fan; and determining said height of the vehicle from the shifted 3D representation in the coordinate system. The disclosed subject matter further relates to an apparatus for performing this method.

What is claimed is: 
     
       1. A method of measuring a height of a vehicle on a road, comprising:
 directing a vehicle classification sensor from a point above the road onto a section of the road and recording, in a given coordinate system, with the vehicle classification sensor a 3D representation of the vehicle passing the section; 
 directing a camera with a known angle of aperture from an elevated point at a side of the road onto the section and recording, with the camera, a 2D image of at least an upper portion of the vehicle and a background above the upper portion of the vehicle; 
 determining an edge profile between the upper portion of the vehicle and the background in the 2D image; 
 establishing, in the coordinate system, a fan of rays each extending from the elevated point and through a different one of multiple points along the edge profile; 
 shifting the 3D representation in the coordinate system in height until it is tangent to said fan; and 
 determining said height of the vehicle from the shifted 3D representation in the coordinate system. 
 
     
     
       2. The method of  claim 1 , wherein said determining the height from the shifted 3D representation in the coordinate system comprises:
 finding a topmost portion of the vehicle in the shifted 3D representation; and 
 measuring the height of the topmost portion of the vehicle in the coordinate system. 
 
     
     
       3. The method of  claim 1 , wherein the vehicle classification sensor triggers the camera when it detects the vehicle to be in front of the camera. 
     
     
       4. The method of  claim 1 , wherein the vehicle classification sensor is a stereoscopic camera or a laser scanner. 
     
     
       5. The method of  claim 1 , wherein the vehicle classification sensor is installed on a gantry spanning the road and the camera is installed on a side pillar of the gantry. 
     
     
       6. An apparatus for measuring a height of a vehicle on a road, comprising:
 a vehicle classification sensor directed from a point above the road onto a section of the road and configured to record, in a given coordinate system, a 3D representation of the vehicle passing the section; 
 a camera with a known angle of aperture directed from an elevated point at a side of the road onto the section and configured to record a 2D image of at least an upper portion of the vehicle and a background above the upper portion of the vehicle; and 
 a processor connected to the vehicle classification sensor and the camera and configured to
 determine an edge profile between the upper portion of the vehicle and the background in the 2D image, 
 establish, in the coordinate system, a fan of rays each extending from the elevated point and through a different one of multiple points along the edge profile, 
 shift the 3D representation in the coordinate system in height until it is tangent to said fan, and 
 determine said height of the vehicle from the shifted 3D representation in the coordinate system. 
 
 
     
     
       7. The apparatus of  claim 6 , wherein the processor is configured to, when determining the height from the shifted 3D representation, find a topmost portion of the vehicle in the shifted 3D representation and measure the height of the topmost portion of the vehicle in the coordinate system. 
     
     
       8. The apparatus of  claim 6 , wherein the vehicle classification sensor or the processor is configured to trigger the camera upon detecting the vehicle to be in front of the camera. 
     
     
       9. The apparatus of  claim 6 , wherein the vehicle classification sensor is a stereoscopic camera or a laser scanner. 
     
     
       10. The apparatus of  claim 6 , wherein the vehicle classification sensor is installed on a gantry spanning the road and the camera is installed on a side pillar of the gantry.